Asset Quality (Credit Card and Other Consumer Loan Classes Asset Quality Indicators) (Details) $ in Millions	Mar. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)		Mar. 31, 2015 USD ($)
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 207,485	[1]	$ 206,696	[1]	$ 204,722
% of Loans	100.00%		100.00%
Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 4,746		$ 4,862
Credit Card [Member] | High Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 33		$ 34
Credit Card [Member] | High Risk [Member] | Ohio [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	16.00%		17.00%
Credit Card [Member] | High Risk [Member] | Pennsylvania [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	16.00%		15.00%
Credit Card [Member] | High Risk [Member] | Michigan [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	7.00%		8.00%
Credit Card [Member] | High Risk [Member] | New Jersey [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	8.00%		8.00%
Credit Card [Member] | High Risk [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	7.00%		7.00%
Credit Card [Member] | High Risk [Member] | Illinois [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	6.00%		6.00%
Credit Card [Member] | High Risk [Member] | Indiana [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	5.00%		6.00%
Credit Card [Member] | High Risk [Member] | Maryland [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	5.00%		4.00%
Credit Card [Member] | High Risk [Member] | Kentucky [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	4.00%
Credit Card [Member] | High Risk [Member] | North Carolina [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	4.00%		4.00%
Credit Card [Member] | High Risk [Member] | All Other States Maximum [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	3.00%		4.00%
Credit Card [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 4,746		$ 4,862
% of Loans	100.00%		100.00%
Weighted average FICO score	734		734
Credit Card [Member] | FICO Score - Greater than 719 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 2,845		$ 2,936
% of Loans	60.00%		60.00%
Credit Card [Member] | FICO Score - 650 to 719 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 1,333		$ 1,346
% of Loans	28.00%		28.00%
Credit Card [Member] | FICO Score - 620 to 649 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 199		$ 202
% of Loans	4.00%		4.00%
Credit Card [Member] | FICO Score - Less than 620 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 219		$ 227
% of Loans	5.00%		5.00%
Credit Card [Member] | No FICO Score Available Or Required [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 150		$ 151
% of Loans	3.00%		3.00%
Other Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 21,479		$ 21,746
Other Consumer Loans [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 14,558		$ 14,533
% of Loans	100.00%		100.00%
Weighted average FICO score	744		744
Other Consumer Loans [Member] | FICO Score - Greater than 719 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 9,424		$ 9,371
% of Loans	65.00%		65.00%
Other Consumer Loans [Member] | FICO Score - 650 to 719 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 3,584		$ 3,534
% of Loans	25.00%		24.00%
Other Consumer Loans [Member] | FICO Score - 620 to 649 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 537		$ 523
% of Loans	4.00%		4.00%
Other Consumer Loans [Member] | FICO Score - Less than 620 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 625		$ 604
% of Loans	4.00%		4.00%
Other Consumer Loans [Member] | No FICO Score Available Or Required [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 388		$ 501
% of Loans	2.00%		3.00%
Other Consumer Loans [Member] | Other Internal Credit Metrics [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 6,921		$ 7,213

[1] Our consolidated assets at March 31, 2016 included the following for which we have elected the fair value option: Federal funds sold and resale agreements of $138 million, Loans held for sale of $1.4 billion, Loans of $.9 billion, and Other assets of $375 million. Our consolidated assets at December 31, 2015 included the following for which we have elected the fair value option: Federal funds sold and resale agreements of $137 million, Loans held for sale of $1.5 billion, Loans of $.9 billion, and Other assets of $521 million.